TiO2/Multi-walled carbon nanotube electrospun nanofibers mats for enhanced Cr(VI) photoreduction

Abstract

Industrial processes, including metal plating and paint production, generate substantial wastewater with hexavalent chromium (Cr(VI)), necessitating the development of efficient photocatalysts for its reduction. In this study, we fabricated curly hybrid nanofiber composites (TiO2/Multi-walled carbon nanotube (MWCNT)) with varying MWCNT contents (0.1, 0.3, 0.5, 0.7, and 1.0 w/w) via electrospinning and subsequent calcination process for Cr(VI) photoreduction efficiency. Our experimental results indicated an initial rise in specific surface areas and micropore volumes with increasing the MWCNT content up to TiO2/MWCNT-7, followed by a decrease, attributed to the development of a curly structure with the introduction of MWCNTs. This improved TiO2 dispersion, reduced the band gap, and densified the composites, enhancing mass transfer properties and visible light utilization. As a result, TiO2/MWCNT-7 exhibited a significant redshift in wavelength along with a 2.93 eV band gap, resulting in 97.5% Cr(VI) photoreduction efficiency within 120 min and sustained 92% efficiency over 6 cycles. This study offers insights for catalyst design and optimization in Cr(VI) photoreduction for water treatment applications.